Applied Environmental Measurement Techniques for Measuring Biodegradable

Carbon (BDOC) in a Continuous The biodegradability of glucose under different conditions has been chosen to evaluate and, based on the results, develop a continuous plug flow bioreactor for biodegradable dissolved organic carbon (BDOC) on-line measurements, as well as to find out what the continuous plug flow bioreactor really measures in terms of BDOC. Plug flow biofilm reactors were colonised by microorganisms indigenous to streamwater and lakewater. Seven different kinds of experiments have been performed, namely experiments with sand-filtered raw water to test the columns, long-term experiments with glucose solution, concentration experiments with glucose solution, hydrodynamic experiments with methylene blue and three different kinds of recirculation experiments with glucose solution. The hydrodynamic experiments demonstrated a retention time of 50 hours or longer for organic molecules in the size range of 200-300 A. This fact proves that the continuous plug flow bioreactor in the case of BDOC on-line measurements only measures an average effect and provides doubtful values for BDOC. Optimisation of retention time by optimising the pore size considering the surface area has been proposed to develop the method. A semi-batch and a trickling bioreactor have been suggested as alternative kinds of reactors for BDOC on-line measurements. Other measurement results have been influenced by the error caused by the wrong retention time or by another error which occurred due to the leakage of organic carbon from connection tubes (Vi ton).